Deformation Processes and Mechanical Properties at Cryogenic Temperatures

Learning Microstructure- and Temperature-Dependencies of Grain Boundary Plastic Deformation Localization via Multi-modal In situ Characterization: Numerous failure mechanisms in engineering alloy parts are correlated to how deformation is transmitted across the boundaries between the microscopic crystals (grains) that comprise the part. Despite extensive study, definitive experimental evidence of the conditions at which deformation will and will not transmit across grain boundaries is elusive, particularly at extreme temperatures in conditions found during space travel or hypersonic propulsion. New electron microscopy and X-ray measurements, which can look in detail at and below the sample surface, are being used together to watch how deformation is transmitted across grain boundaries as it occurs. Using these measurements and machine-learning techniques, a set of rules are being established describing how deformation is transmitted as a function of temperature in a range of model atomic crystal structures representing various forms of commonly used structural alloys. These rules can then be used to improve the usage of existing alloys in the field and to design new high-performance alloy systems.